The recent evolution of data transmission has led to higher and higher bitrates. For long-haul digital transmission, optical transmission has long been preferred over electrical transmission, because of its lower losses and longer span lengths that can be bridged without signal regeneration. Now, the introduction of digitals signals at bitrates of 10 Gbit/s and more, requires to deploy optical transmission also for short range applications such as local area networking or inter-rack communication or even on-board optical signal transport. However, signal processing as such will remain electrical in most cases. This imposes a need for low-cost electrical transmitter and receiver components, which pre-process received optical signals and electrical signals to be transmitted optically.
Moreover, at bitrates of 10 Gbit/s and more, optical dispersion and other distorting effects in optical waveguides become predominant, thus requiring some sort of compensation techniques to restore a digital signal after optical transmission. FIG. 3 shows a classical approach of dispersion compensation in optical transmission systems. A dispersion compensation unit 303 is inserted after a fiber link 302 to compensate fiber distortion of an optical signal transmitted by an optical signal source 301. After dispersion compensation, the signal is fed to the actual optical receiver 304. Typical dispersion compensation units consist of one or more optical amplifier (e.g., EDFA) and a dispersion compensating fiber.
As a general rule, it can be said that the higher the bitrate, the shorter the maximum distance between two signal regenerators. On the other hand, signal distortion strongly depends on the type of waveguide used, e.g., single-mode or multi-mode silica fiber or plastic fiber. Typically, the different signal propagation conditions in different types of waveguides would lead to the development of different compensation units for the various waveguide types, which would increase development and production costs per unit.
It is therefore an object of the present invention to provide an integrated optical transceiver circuit capable to be used under different transmission conditions.